Transcript 690Session3B

LBSC 690
Session 3
Networking
Analog to Digital
We live in an analog world:
Sound, temperature, light, etc.

Sensory inputs.
Are continuous signals.
Can assume all (essentially infinite) values in a
given interval.
Basis for analog computers:

Uses electrical voltage/current to variables. to represent.
Digital
Discrete representation: assumes a finite
number of values in a given interval.
Basis for digital computers:

Use 2 discrete values to represent data, &
instructions. (Binary system).
Analog signals converted to digital by Pulse
Code Modulation (PCM).
PCM
Three step process:
Analog signal is sampled:

Nyquist’s Theorem.
Samples are quantized.
Quantized samples are encoded into binary
digits, called “bits” for short.
See handout.
Evolution
Computers initially stand alone.
Need to communicate.

Transmit data at a distance.
Communications:


Data communication.
Telecommunication:

Provides electrical communications at a distance.
Service provided by a number of companies
internationally.

The “telecommunications industry.”
Telecommunications Industry
Carriers:


LECs (RBOCs: 7 to 4); CLECs.
IXCs.
Internet Service Providers (ISPs).
Vendors/Consultants & Manufacturers.
Judicial/Political/Legislative:

Regulatory agencies.
Standards Making Organizations.
Customers: business & residential.
Technology and research.
Networking
Simplest form:
Directly connect two communicating
devices.
Not practical solution.

Problem of topology:

How to deal with fully connected mesh.
Need network.

Nodes and segments.
The Universal Seven Part Data
Model
DTE
DCE
DTE/DCE
Interface
DCE
Transmission
Channel
DTE
DCE/DTE
Interface
DTE: Data Terminal Equipment
DCE: Data Communication Equipment
Network (Cont’d.)
S
N
“Local loop”
NETWORK
S
S: Network Station
N
N
N: Network Node
S
N
S
Network Types
Switched Communication Network:
Circuit-switched.
Packet–-switched.
Broadcast communication Network:
Packet radio network.
Satellite network.
Local area network.
Generic Switching Network
Reference handout.
Concepts:
Bandwidth

Measure of channel capacity: frequency range
Radio Spectrum (Next Slide)

Frequencies available for telecommunications
Modulation

Process of embedding intelligence in a carrier wave
Multiplexing


Process that combines multiple calls or messages on a
single channel
Examples; TDMA (Time Division Multiple Access),
CDMA (Code Division Multiple Access)
Spectrum
A limited resource

Government controlled: FCC & ITU, e.g.
Some assigned frequencies:








Am radio: 535-1635 KHz
Analog cordless phones: 44-49 MHz
TV channels 2-6: 54-88 MHz
FM radio: 88-108 MHz
TV channels 7-13: 174-216 MHz
Cellular phones: 806-890 MHz
PCS: 900-929 MHz
Satellite TV (small dish): 11.7-12.7 GHz
Cell Phones
More than 115 million users in US

46,000 people subscribing every day
Based on concept of cells


10 sq. mi. in area with a Base Station in it
Low power: 0.3 & 6 watts
Mobile Telephone Switching Office (MTSO).
Special codes: electronic serial no. (ESN), mobile
identif. no.(MIN, system ident, code (SID).
Analog vs. digital.
American vs. European approaches


GSM (Global System For Mobile communication)
TDMA vs. CDMA
LANs
What are they?
Need & functions.
Hardware/software components.
Concept of packets.
Ethernet and token ring.

ANSI/ IEEE 802.3 (ISO 8802-3)
Need to interconnect LANs.
LANs
Data communication facilities designed to
provide high-speed switched connections
between processors peripherals and
terminals within a local area, e.g., buildings
or a campus.
LAN Functions
File sharing
Printer sharing
CD ROM sharing
On-line databases
Groupware
OPAC access
Dial in & out
Fax in & out
Voice-video-multimedia
E-mail
Internet access
LAN Benefits
Shared access
Increased security
Application and data highway

Adding new applications is done once (on
server)
Support services more effective and lower
cost
LAN Installation
Network Operating System (NOS).
Network Interface Cards (NIC).
Cabling and connectors.
Hubs/ Switches.
Network Servers:

File, Print, Communication, etc.
Clients
TRAINING
Network Management:
Network Administrator & Support Personnel.
 Certification.
 Continuing education.

User training.
Ethernet
Developed in 1973 at Xerox Corporation’s Palo
Alto Research Center (PARC).
Developed by Bob Metcalfe.
Uses the Ethernet Protocol.
Protocol: A code prescribing strict adherence to
correct etiquette and precedence.
Communication protocols: symbols (Character
set), rules for sequence and timing of messages,
and procedures for error detection and handling.
Messages broken into frames (packets).
 With source and destination addresses.
Ethernet
Broadcast network
Carrier Sense Multiple Access/Collision Detection
(CSMA/CD)
Collision retry (random wait)
Need for repeaters
Hubs

Basic, Smart, Intelligent, Switches
Bridges
Routers (internetting)
Network Topology
Bus
Star
Ring
Mesh
Hybrid
Transmission Channels (Media)
4-wire phone
UTP
STP
Coax
Fiber optic
3Kbps
100Mbps
16Mbps
10Mbps
10Gbps
200 ft.
100 ft.
100 ft.
500 ft.
2-5 km.
The Internet
Historical development.
TCP/IP Protocol Suite.
Telnet.
FTP.
E-mail.
Assignment 1:

Two exercises.
Packet switching.
Addressing: URLs.
Packet Switched Networks
General Switching Diagram:

Reference Handout
Modems
Function:

Modulation – demodulation.
Types and speeds:
Standard
 ISDN.
 Cable TV.
 xDSL.
 Satellite

World Wide Web (WWW)
Historical development.
HTTP.
HTML.
XML.
Multimedia.
Trends
Convergence.
Voice over IP (VIP).
Wireless.
3G (Third Generation)
 PCS (Personal Communication Services)

Ubiquitous networking
Remote device control.